soc: arm: move init code from SYS_INIT to hooks

Replace SYS_INIT with SoC hooks and adapt SoC init code

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

soc/arm/beetle/Kconfig

@@ -8,3 +8,4 @@ config SOC_SERIES_BEETLE
 	select CPU_CORTEX_M3
 	select CPU_HAS_ARM_MPU
 	select CPU_CORTEX_M_HAS_DWT
+	select SOC_EARLY_INIT_HOOK

soc/arm/beetle/soc.c

@@ -21,19 +21,9 @@
  * @brief Perform basic hardware initialization at boot.
  *
  * This needs to be run from the very beginning.
- * So the init priority has to be 0 (zero).
- *
- * Assumption:
- * MAINCLK = 24Mhz
- *
- * @return 0
  */
-static int arm_beetle_init(void)
+void soc_early_init_hook(void)
 {
 	/* Setup various clocks and wakeup sources */
 	soc_power_init();
-
-	return 0;
 }
-
-SYS_INIT(arm_beetle_init, PRE_KERNEL_1, 0);